<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			.header,.footer{
				width: 700px;
				height: 100px;
				background-color: aquamarine;
				margin: 10px auto;
			}
			.main{
				width: 700px;
				height: 400px;
				margin: 0 auto;
			}
			.contentCenter{
				width: 500px;
				height: 400px;
			}
			.centertop{
				width: 500px;
				height: 200px;
				background-color: darkgoldenrod;
			}
			.centerbottom{
				width: 500px;
				height: 200px;
				background-color: cornflowerblue;
			}
			.sidebar{
				width: 100px;
				height: 400px;
				background-color: royalblue;
				margin: 0px 0px;
			}
			.content{
				width: 500px;
				height: 225px;
				background-color: darkgoldenrod;
			}
			.left{
				float: left;
			}
			.right{
				float: right;
			}
		</style>
	</head>
	<body>
		<!--头部-->
		<div class="header">头部</div>
		<!--中部-->
		 <div class="main">
		 	<!--左-->
		 	<div class="sidebar left">左</div>
		 	<!--中-->
		 	<div class="contentCenter left">
		 		<div class="centertop">中上</div>
		 		<div class="centerbottom">中下</div>
		 	</div>
			 <!--右-->
		 	<div class="sidebar right">右</div>
		 </div>
		 <!--尾部-->
		<div class="footer">尾部</div>
		
		
	</body>
</html>
